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Mathlib.Topology.Algebra.StarSubalgebra

Topological star (sub)algebras #

A topological star algebra over a topological semiring R is a topological semiring with a compatible continuous scalar multiplication by elements of R and a continuous star operation. We reuse typeclass ContinuousSMul for topological algebras.

Results #

This is just a minimal stub for now!

The topological closure of a star subalgebra is still a star subalgebra, which as a star algebra is a topological star algebra.

theorem StarSubalgebra.embedding_inclusion {R : Type u_1} {A : Type u_2} [CommSemiring R] [StarRing R] [TopologicalSpace A] [Semiring A] [Algebra R A] [StarRing A] [StarModule R A] {S₁ : StarSubalgebra R A} {S₂ : StarSubalgebra R A} (h : S₁ S₂) :

The StarSubalgebra.inclusion of a star subalgebra is an Embedding.

theorem StarSubalgebra.closedEmbedding_inclusion {R : Type u_1} {A : Type u_2} [CommSemiring R] [StarRing R] [TopologicalSpace A] [Semiring A] [Algebra R A] [StarRing A] [StarModule R A] {S₁ : StarSubalgebra R A} {S₂ : StarSubalgebra R A} (h : S₁ S₂) (hS₁ : IsClosed S₁) :

The StarSubalgebra.inclusion of a closed star subalgebra is a ClosedEmbedding.

The closure of a star subalgebra in a topological star algebra as a star subalgebra.

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    theorem StarSubalgebra.topologicalClosure_mono {R : Type u_1} {A : Type u_2} [CommSemiring R] [StarRing R] [TopologicalSpace A] [Semiring A] [Algebra R A] [StarRing A] [StarModule R A] [TopologicalSemiring A] [ContinuousStar A] :
    Monotone StarSubalgebra.topologicalClosure
    @[reducible]

    If a star subalgebra of a topological star algebra is commutative, then so is its topological closure. See note [reducible non-instances].

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      @[reducible]
      def StarSubalgebra.commRingTopologicalClosure {R : Type u_4} {A : Type u_5} [CommRing R] [StarRing R] [TopologicalSpace A] [Ring A] [Algebra R A] [StarRing A] [StarModule R A] [TopologicalRing A] [ContinuousStar A] [T2Space A] (s : StarSubalgebra R A) (hs : ∀ (x y : s), x * y = y * x) :

      If a star subalgebra of a topological star algebra is commutative, then so is its topological closure. See note [reducible non-instances].

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        Continuous StarAlgHoms from the topological closure of a StarSubalgebra whose compositions with the StarSubalgebra.inclusion map agree are, in fact, equal.

        theorem StarAlgHomClass.ext_topologicalClosure {R : Type u_1} {A : Type u_2} {B : Type u_3} [CommSemiring R] [StarRing R] [TopologicalSpace A] [Semiring A] [Algebra R A] [StarRing A] [StarModule R A] [TopologicalSemiring A] [ContinuousStar A] [TopologicalSpace B] [Semiring B] [Algebra R B] [StarRing B] [T2Space B] {F : Type u_4} {S : StarSubalgebra R A} [FunLike F ((StarSubalgebra.topologicalClosure S)) B] [AlgHomClass F R ((StarSubalgebra.topologicalClosure S)) B] [StarAlgHomClass F R ((StarSubalgebra.topologicalClosure S)) B] {φ : F} {ψ : F} (hφ : Continuous φ) (hψ : Continuous ψ) (h : ∀ (x : S), φ ((StarSubalgebra.inclusion ) x) = ψ ((StarSubalgebra.inclusion ) x)) :
        φ = ψ

        The topological closure of the subalgebra generated by a single element.

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          The coercion from an elemental algebra to the full algebra as a ClosedEmbedding.

          theorem elementalStarAlgebra.starAlgHomClass_ext (R : Type u_1) {A : Type u_2} {B : Type u_3} [CommSemiring R] [StarRing R] [TopologicalSpace A] [Semiring A] [StarRing A] [TopologicalSemiring A] [ContinuousStar A] [Algebra R A] [StarModule R A] [TopologicalSpace B] [Semiring B] [StarRing B] [Algebra R B] [T2Space B] {F : Type u_4} {a : A} [FunLike F ((elementalStarAlgebra R a)) B] [AlgHomClass F R ((elementalStarAlgebra R a)) B] [StarAlgHomClass F R ((elementalStarAlgebra R a)) B] {φ : F} {ψ : F} (hφ : Continuous φ) (hψ : Continuous ψ) (h : φ { val := a, property := } = ψ { val := a, property := }) :
          φ = ψ